This is driving me nuts. When I save a photoshop file as a .png at 300 ppi, when I open it it is 299.999 ppi.
I wouldn't mind for my personal use, but these are digital files I sell. Believe me, I will get emails about it.
Even when I open the .png file and change the ppi to 300, if I open it again it's once again 299.999!
I am saving files with a transparent background with compression no interlacing. I'm using save as, not save for web.
Here's the interesting thing.
1. This started happening when I got my new iMac with Lion and installed CS6. Did both at the same time.
2. My assistant, this happens with my assistant who is on PC with Photoshop CS5.
What's going on and how can I fix this?
I did find this article.
"Most other programs do store and use the correct scaled resolution value in PNG files. PNG stores resolution internally as pixels per meter, so when calculating back to pixels per inch, some programs may show excessive decimal digits, perhaps 299.999 ppi instead of 300 ppi (no big deal)."
I don't know why this has started happening in CS6 though. Didn't happen in CS5. Hmm. Actually, I do have CS5 installed. Maybe I should try doing my pngs in it again.
Just searched around the web. I guess this is a common occurance. I'll just have to put it in my support FAQS that this is normal and doesn't affect the image.
You are talking about a miniscule rounding error. If it bothers you or your clients you might try the PS Scripting forum for a simple script to put it back to 300 if it occurs.